The present invention relates generally to vehicle positioning systems and more particularly to a method of triggering the vehicle positioning system to transmit the vehicle location to a remote location.
Several types of known vehicle positioning systems transmit the position of a remote vehicle to another location. For example, an emergency assistance request system on a vehicle transmits the location of the vehicle to an emergency assistance dispatch station along with a request for assistance. As another example, vehicle positioning systems are installed on fleets of vehicles so that their location and progress can be tracked from a central location.
These known systems use Global Positioning System (GPS) position solutions, generally in conjunction with other sensors, to obtain an estimated position. This solution is generally in terms of a standard navigational reference frame, for example WGS-84 (World Geodetic System—latitude and longitude), earth-centered-earth-fixed (ECEF). Many such coordinate systems or reference frames have been developed and are used by the military and by civilians for navigation and more generally to describe a position on earth.
It is desirable to provide timely vehicle location updates to the remote location. However, more frequent transmission than necessary increases cost and lowers communications channel capacity which may result in increased time necessary to receive the vehicle location data. Previously, the vehicle location has been transmitted to the remote location at preset intervals or upon request of the remote location. For example, the vehicle location may be sent at hourly intervals. Another method transmits the vehicle location whenever the vehicle changes direction. The problem with these triggering methods is that the transmission is not triggered by any meaningful event, which may result in the vehicle location being transmitted too frequently or not frequently enough.
Vehicle location for services such as fleet management, emergency notification, autonomous vehicle location, etc. can therefore benefit greatly from transmission of the vehicle position triggered by a meaningful event, such as change in information.